Table of Contents
Advertisement
3. Confirm using black & white pattern and a white
screen the color balance (gray scale and white
balance). If white balance is required perform the
following:
Procedure (low lights):
1. Apply a Black & White pattern.
2. Connect a jumper from the base of Q452 to cold
ground (
) (or apply +2.5V DC to TP1 to defeat
the neck protector circuit).
3. Set the red and blue cut-off registers (C00 and
C02) to 00.
4. On the remote control, press R-TUNE to get a
green horizontal line.
5. Connect the scope between GRN cathode (GK, on
the CRT-Board) and cold ground (
6. View scope trace at Horizontal rate and adjust the
service mode DAC (C01) level until 195V for 25",
27" & 32" above DC ground is measured and
175V for 20", as indicated in Fig. 20.
195VDC (25", 27", 32")
175VDC (20")
Figure 20. Cathode waveform, adjustment
waveform detail
7. Adjust screen VR (on T551, flyback) until the green
line just becomes visible.
8. Press R-TUNE (on remote control) to display full
screen.
9. Select red cut-off register (C00). Press R-TUNE to
display a green horizontal line. Increase C00 value
(using volume on remote) until the line turn yellow
(mixing green & red).
10. Press R-TUNE to display full screen.
11. Select blue cut-off register (C02) and press
R-TUNE to see the yellow line. Increase C02 value
(using Vol on remote) until the line becomes white
(mixing red blue and green).
12. Press R-TUNE to display full screen.
13. Confirm that a good gray scale is displayed when
viewing a black & white pattern.
14. Exit the service mode.
White balance (high lights)
1. Using a black and white pattern and white screen
adjust red drive, C03, and blue drive, C05 to obtain
good white level on screen. If white looks reddish,
decrease C03, if white looks bluish, decrease C05.
2. Exit service mode.
3. In picture menu change picture and brightness
from low to high scales and observe black and
white tracking.
4. If corrections are required, repeat step 1 until the
correct balance is achieved.
5. Following satisfactory high lights adjustment
perform the following white balance touch-up.
White balance touch-up procedure:
Use this procedure to make minor adjustment to white
balance.
1. Enter service mode.
2. Apply a black and white (B/W) signal (signal that
includes gray tones).
3. Observe low and high brightness areas of a B/W
picture for proper tracking. Adjust the following as
required for "good gray scale and warm highlights":
•
HIGH LIGHT areas – Adjust red drive (C03) and
blue drive (C05) registers until picture appear best
for warm whites.
•
LOW LIGHT areas – adjust red cut-off (C00) and
blue cut-off (C02) registers until best picture for
black-gray.
).
Due to effect from low level adjustment on high level
adjustment, it is recommended that this procedure is
done at the end of the adjustments procedure.
4. Exit service mode.
5. Remove all external connections made to the
receiver.
Sub-Brightness final adjustment
Service DAC adjustment (B02)
This adjustment should be made last, following
0V DC
other picture adjustments.
Preparation:
1. Turn the receiver ON and allow 20 minute warm up
at high brightness (white screen).
2. Apply a black and white cross pattern.
3. Set PICTURE to max.
4. Set BRIGHT to center.
Procedure:
1. In service mode, select sub bright register (B02).
2. Adjust B02 until the 7.5 IRE section looks same as
3.0 IRE section as seen in Fig. 21.
3. Exit service mode.
Horizontal centering
Service DAC adjustment (C09)
Preparation:
Connect a monoscope generator.
Procedure:
1. In the service mode, select the horizontal centering
adjustment DAC (C09). Adjust it until locations "A"
and "B" are even on both sides of screen, as
indicated in Fig. 22.
2. Exit the service adjustment mode.
- 22 -
Figure 21. Sub-bright adjustment
Advertisement
Table of Contents
